Indeed, I think a lot of people miss that the nature of public property and governments not being able to censor free speech did basically guarantee people an audience in the olden days. Did you have a message you wanted people to hear? Protest in a heavily trafficked area (like a town centre), and you had an audience of thousands or even millions, regardless of whether they wanted to hear what you had to say or not.

Imagine how much less useful political movements would be if corporations owned everything in the real world and the people protesting had to do so in their own homes/some private property away from the public. That's the situation these social media sites have set up.

But hey, I guess it's not a new thing, nor an issue exclusive to the internet. In some places, a shopping mall or other corporate property might be the 'heart of the local community', and like with Twitter and Facebook, they could ban those they don't like and de facto censor their speech too.

And what are the alternative services that these people should use? Google, Facebook, Twitter, etc. simply don't have any alternatives that are widely used or credible.